Flexible circuit boards, which have small volume and are capable of withstanding millions of dynamic bendings, and are gradually taking the place of wiring harnesses in the prior art, which have large volume and are not easy to bend. In terms of a thin and light device with a compact and complex internal structure, the total weight and volume of a flexible assembly is reduced by 70%, compared to those of a conventional round conductor harness. With continuous developments of technologies, flexible circuit boards will be the unique solution for satisfying compact and mobile requirements of an electronic component.
A conventional flexible circuit board is to etch a copper foil circuit board on a base layer, and conductive traces are visible from its appearance, so the conventional flexible circuit board is not suitable for manufacturing a fully transparent electronic device which is currently prevalent on the market.
In addition, the conventional flexible circuit board is to etch a copper foil circuit board on a base layer, and its manufacture processes mainly include: exposing->developing->circuit etching->removing undesirable copper foil->surface treating and the like. Restricted by copper foil materials and manufacture processes, the conventional copper foil fails to obtain a high-density circuit trace in the process of etching, and thus will occupy more space when is connected inside of a device.